Easy-to-notice type name of config struct (#22)

* fix: stylecheck ST1017 - no Yoda conditions

  - ST1017: don't use Yoda conditions ()

* update: go.mod (Cobra version)

* feat: enable more linters (golangci-lint)

* feat: TConfigApp -> TConfigFile

* feat: linter (gospec, prealloc and predeclared)

* chore: add reference URL for lint errors

Author: KEINOS

.github/golangci.yml

@@ -7,6 +7,8 @@ run:
   # include test files or not, default is true
   tests: true
 
+  fast: true
+
   # list of build tags, all linters use it. Default is empty list.
   build-tags:
     - golangci
@@ -38,9 +40,10 @@ output:
 # enabled linters. Conf settings follows.
 linters:
   enable:
+    - deadcode # Finds unused code
     - dogsled
     - dupl
-    - errcheck
+    - errcheck # Errcheck is a program for checking for unchecked errors in go programs. These unchecked errors can be critical bugs in some cases
     - funlen
     - gocognit
     - gocritic
@@ -50,8 +53,11 @@ linters:
     - gofmt
     - gofumpt     # Stricter gofmt
     - golint
-    - govet
+    - gosec       # Inspects source code for security problems
+    - gosimple    # Linter for Go source code that specializes in simplifying a code
+    - govet       # Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string
     - ifshort
+    - ineffassign # Detects when assignments to existing variables are not used
     - lll
     - maligned
     - megacheck   # gosimple, staticcheck, unused
@@ -60,9 +66,17 @@ linters:
     - nestif      # Limit if statements nested deep
     - nolintlint  # Don't allow 'nolint' annotation w/out a description
     - nlreturn    # Requires a new line before return
+    - prealloc    # Finds slice declarations that could potentially be preallocated
+    - predeclared # Find code that shadows one of Go's predeclared identifiers
+    - staticcheck # Staticcheck is a go vet on steroids, applying a ton of static analysis checks
+    - structcheck # Finds unused struct fields
+    - stylecheck
+    - typecheck   # Like the front-end of a Go compiler, parses and type-checks Go code
     - unconvert   # Detect unnecessary type conversions
+    - unused      # Checks Go code for unused constants, variables, functions and types
     #- testpackage # Limit use unexported functions and methods from source code in tests
     - thelper     # Enforce to call 't.Helper()' in the test helper function
+    - varcheck    # Finds unused global variables and constants
     - whitespace  # Limit unnecessary newlines at the start and end of functions, if, for, etc
     - wsl         # Enforce empty lines at the right places to make code more readable.
 

.github/run-tests-lint.sh

@@ -10,6 +10,7 @@
 #  Constants
 # -----------------------------------------------------------------------------
 PATH_DIR_PARENT="$(dirname "$(cd "$(dirname "${BASH_SOURCE:-$0}")" && pwd)")"
+PATH_FILE_CONF_GOLANGCILINT="${PATH_DIR_PARENT}/.github/golangci.yml"
 SUCCESS=0
 FAILURE=1
 
@@ -24,11 +25,16 @@ cd "${PATH_DIR_PARENT}" || {
     exit $FAILURE
 }
 
-if ! golangci-lint run --config ./.github/golangci.yml ./...; then
+echo "${@}" | grep -e "-l" -e "--linters" >/dev/null && {
+    golangci-lint linters --config "$PATH_FILE_CONF_GOLANGCILINT" ./...
+}
+
+if ! golangci-lint run --config "$PATH_FILE_CONF_GOLANGCILINT" ./...; then
     echo >&2
-    echo >&2 'References for debugging:'
-    echo >&2 '  wsl    : https://github.com/bombsimon/wsl/blob/master/doc/rules.md'
-    echo >&2 '  gofumpt: https://github.com/mvdan/gofumpt#added-rules'
+    echo >&2 'References for debugging lint error:'
+    echo >&2 '  wsl     : https://github.com/bombsimon/wsl/blob/master/doc/rules.md'
+    echo >&2 '  gofumpt : https://github.com/mvdan/gofumpt#added-rules'
+    echo >&2 '  * for other lint errors see: https://golangci-lint.run/usage/linters/'
     exit $FAILURE
 fi
 

cmd/cmd_helloExtended.go

@@ -63,14 +63,14 @@ func getMsgToGreet(args []string) string {
 		argJoined string = strings.TrimSpace(strings.Join(args, " ")) // get arg value
 	)
 
-	if "" != greetTo && "" != argJoined {
+	if greetTo != "" && argJoined != "" {
 		to = greetTo + " and " + argJoined
 	} else {
-		if "" != greetTo {
+		if greetTo != "" {
 			to = greetTo
 		}
 
-		if "" != argJoined {
+		if argJoined != "" {
 			to = argJoined
 		}
 	}

cmd/cmd_helloExtended_test.go

@@ -113,16 +113,16 @@ func convertShellArgsToSlice(t *testing.T, str string) []string {
 		t.Fatalf("args parse error: %+v\n", err)
 	}
 
-	if 0 == len(cmdArgs) {
+	if len(cmdArgs) == 0 {
 		t.Fatalf("args parse error. Command contains fatal strings: %+v\n", str)
 	}
 
 	// `hello cmd` dependent check
-	if "hello" != cmdArgs[0] {
+	if cmdArgs[0] != "hello" {
 		t.Fatal("format error. The command must start with 'hello'.")
 	}
 
-	if "ext" != cmdArgs[1] {
+	if cmdArgs[1] != "ext" {
 		t.Fatal("format error. The command must start with 'hello cmd'.")
 	}
 

cmd/cmd_root.go

@@ -78,12 +78,12 @@ func init() {}
 
 // loadConfig sets the object in the arg with the results exits with an error if user defined conf file didn't exist.
 // Otherwise searches the default file and if not found then use the default value.
-func loadConfig(configApp *conf.TConfigApp, configUser interface{}) {
+func loadConfig(configApp *conf.TConfigFile, configUser interface{}) {
 	// Overwrite "configUser" with conf file value if file found.
-	if err := conf.LoadConfig(*configApp, &configUser); err != nil {
+	if err := conf.LoadFile(*configApp, &configUser); err != nil {
 		// Exits if user defined conf file fails to read
-		if "" != configApp.PathFileConf {
-			msg := fmt.Errorf("Failed to read configuration file.\n  Error msg: %v", err)
+		if configApp.PathFileConf != "" {
+			msg := fmt.Errorf("failed to read configuration file.\n  Error msg: %v", err)
 			osExit(EchoStdErrIfError(msg))
 		}
 		// Conf file not found. Using default. Set flag to true.

cmd/cmd_root_test.go

@@ -19,7 +19,7 @@ func Test_loadConfig_UserDefinedPath_Fails(t *testing.T) {
 		expectExitCode int
 		actualExitCode int = 0 // This should turn into 1
 
-		confAppDummy  conf.TConfigApp
+		confAppDummy  conf.TConfigFile
 		confUserDummy struct {
 			NameToGreet string `mapstructure:"name_to_greet"` // // Dont'f forget to define `mapstructure`
 		}
@@ -32,7 +32,7 @@ func Test_loadConfig_UserDefinedPath_Fails(t *testing.T) {
 
 	var capturedMsg string = capturer.CaptureStderr(func() {
 		// Test user defined bad (non-existing) file path
-		confAppDummy = conf.TConfigApp{
+		confAppDummy = conf.TConfigFile{
 			PathFileConf: "./foobar.json",
 			PathDirConf:  "",
 			NameFileConf: "",
@@ -48,7 +48,7 @@ func Test_loadConfig_UserDefinedPath_Fails(t *testing.T) {
 		"If user defined path doesn't exist then should exit with 1. Captured STDERR: "+capturedMsg,
 	)
 	// containing error message assertion
-	assert.Contains(t, strings.TrimSpace(capturedMsg), "Failed to read configuration file")
+	assert.Contains(t, strings.TrimSpace(capturedMsg), "failed to read configuration file")
 }
 
 func Test_loadConfig_UseDefault(t *testing.T) {
@@ -63,7 +63,7 @@ func Test_loadConfig_UseDefault(t *testing.T) {
 		expectFlag     bool
 		actualFlag     bool
 
-		confAppDummy  conf.TConfigApp
+		confAppDummy  conf.TConfigFile
 		confUserDummy struct {
 			NameToGreet string `mapstructure:"name_to_greet"` // // Dont'f forget to define `mapstructure`
 		}
@@ -76,7 +76,7 @@ func Test_loadConfig_UseDefault(t *testing.T) {
 
 	var capturedMsg string = capturer.CaptureStderr(func() {
 		// Test app defined non-existing file path
-		confAppDummy = conf.TConfigApp{
+		confAppDummy = conf.TConfigFile{
 			PathFileConf: "",
 			PathDirConf:  ".",
 			NameFileConf: "dummy_config",

cmd/common.go

@@ -35,7 +35,7 @@ type TConfUser struct {
 
 var (
 	// ConfApp is the basic app settings.
-	ConfApp = conf.TConfigApp{
+	ConfApp = conf.TConfigFile{
 		PathDirConf:        ".",
 		NameFileConf:       "config",
 		NameTypeConf:       "json",

conf/README.md

@@ -1,10 +1,10 @@
-# Package conf
+# package conf
 
-Directory of file-configuration package using [Viper](https://github.com/spf13/viper).
+Package `conf` reads values from a configuration file such as JSON, TOML, YAML and etc using [Viper](https://github.com/spf13/viper).
 
-- Note that this package may be used as JSON/YAML file reader but it's not designed to load MEGA sized file.
+- Note: Eventhough this package may be used as a file loader of JSON/YAML/etc but it's NOT designed to load a huge-size-file.
 
-## Sample usage in other package
+## Sample usage
 
 Pretend the user config file (`userConfig.json`) was as below:
 
@@ -28,13 +28,13 @@ type TDataUser struct {
 }
 
 var (
-    configFile = conf.TConfigApp{
+    configFile = conf.TConfigFile {
         PathDirConf:        ".",
         NameFileConf:       "userConfig",
         NameTypeConf:       "json",
     }
 
-    userValues = TDataUser{
+    userValues = TDataUser {
         MyValue: "default value",
     }
 )
@@ -47,6 +47,11 @@ if err := conf.LoadConfig(*configFile, &userValues); err != nil {
 // Use loaded value from the conf file
 myValue := userValues.MyValue
 
-// `myValue` expects to be "Cobra"
+// `myValue` expects to be "Cobra". If "./userConfig.json" didn't exist
+// then the value should be "default value".
 
 ```
+
+## TODO
+
+- [ ] Map the values from ENV variables that match

conf/config.go

@@ -1,5 +1,5 @@
 /*
-Package conf config.go defines functions to read file configuration using Viper.
+Package conf reads values from a configuration file such as JSON, TOML, YAML and etc using Viper.
 
 It was separated to a different package from `cmd` to ease testing and re-use.
 
@@ -19,24 +19,29 @@ import (
 	"github.com/spf13/viper"
 )
 
-// TConfigApp defines the data structure to store basic config of the app.
-type TConfigApp struct {
-	// one-liner-conf
+// TConfigApp is an alias of TConfigFile for backward compatibility and it will be removed in v1.3.0.
+// Deprecated: as of v1.2.1. Use TConfigFile instead.
+type TConfigApp = TConfigFile
+
+// TConfigFile defines the data structure to store the information of the file to load.
+type TConfigFile struct {
+	/* one-liner-conf of file path */
 
 	PathFileConf string // File path of config. If set, will have priority than NameFileConf and PathDirConf.
 
-	// parted conf
+	/* parted conf of file path */
 
 	PathDirConf  string // Dir path of config to search.
 	NameFileConf string // File name of config file. May or may not have an extension.
 	NameTypeConf string // File extension. REQUIRED if the conf file does not have the extension.
 
+	/* configuration of it's state */
 	IsUsingDefaultConf bool // Flag to determine if the app is using the default value or conf file value.
 }
 
-// GetNameConf is a method of TConfigApp that returns the config file name.
-func (c TConfigApp) GetNameConf() string {
-	if "" != c.PathFileConf {
+// GetNameConf is a method of TConfigFile that returns the config file name.
+func (c TConfigFile) GetNameConf() string {
+	if c.PathFileConf != "" {
 		return filepath.Base(c.PathFileConf)
 	}
 
@@ -47,19 +52,23 @@ func (c TConfigApp) GetNameConf() string {
 	return c.NameFileConf + "." + c.NameTypeConf
 }
 
-// LoadConfig() stores values from the config file or env variables to userConfig.
+// LoadConfig is an alias of LoadFile for backward compatibility and it will be removed in v1.3.0.
+// Deprecated: as of v1.2.1. Use LoadFile() instead.
+var LoadConfig = LoadFile
+
+// LoadFile() stores values from the config file to userConfig.
 //
 // @args
-//     appConfig  TConfigApp : Basic configuration to read the conf file.
-//     userConfig struct     : An object to store values from conf file.
+//     appConfig  TConfigFile : Basic configuration to read the conf file.
+//     userConfig struct      : An object to store values from conf file.
 // @return
-//     err        error      : If fails to read/store values from conf file returns error othersise nil.
+//     err        error       : If fails to read/store values from conf file returns error othersise nil.
 // Usage:
 //   type TConfUser struct {
 //       MyValue string `mapstructure:"my_value"`
 //   }
 //   var (
-//       configApp = conf.TConfigApp{
+//       configApp = conf.TConfigFile{
 //           PathDirConf:        ".",
 //           NameFileConf:       "userConfig",
 //           NameTypeConf:       "json",
@@ -68,33 +77,30 @@ func (c TConfigApp) GetNameConf() string {
 //           MyValue: "",
 //       }
 //   )
-//   if err := conf.LoadConfig(*configApp, &configUser); err != nil {
+//   if err := conf.LoadFile(*configApp, &configUser); err != nil {
 //       // do something with the error
 //   }
 //   myValue := configUser.MyValue
-func LoadConfig(appConfig TConfigApp, userConfig interface{}) (err error) {
-	// Reset current stored values in viper
-	viper.Reset()
-
-	// Read values from the ENV variable if set
-	viper.AutomaticEnv()
+func LoadFile(appConfig TConfigFile, userConfig interface{}) (err error) {
+	// pitViper is a temporary viper instance
+	pitViper := viper.New()
 
 	// Set file path to search
-	if "" != appConfig.PathFileConf {
+	if appConfig.PathFileConf != "" {
 		// Set one-liner file path
-		viper.SetConfigFile(appConfig.PathFileConf)
+		pitViper.SetConfigFile(appConfig.PathFileConf)
 	} else {
 		// Set inidividual file path info
-		viper.AddConfigPath(appConfig.PathDirConf)
-		viper.SetConfigName(appConfig.NameFileConf)
-		viper.SetConfigType(appConfig.NameTypeConf)
+		pitViper.AddConfigPath(appConfig.PathDirConf)
+		pitViper.SetConfigName(appConfig.NameFileConf)
+		pitViper.SetConfigType(appConfig.NameTypeConf)
 	}
 
 	// Search and read values from the config file and stores to "userConfig"
-	err = viper.ReadInConfig()
+	err = pitViper.ReadInConfig()
 	if err == nil {
 		// Map the read config values
-		err = viper.Unmarshal(&userConfig)
+		err = pitViper.Unmarshal(&userConfig)
 	}
 
 	return err // return error if viper fails to read or map the values